Help configuring .yml for to publish a stream with FFmpeg

[seabass1217]

I'm trying to publish a rtsp stream from OpenCV via rtsp-simple-sever with FFmpeg. I'm using a Jetson NX to connect to a rtsp server on a wireless IP camera that outputs a 30 fps, 720p stream. I want to republish to rtsp-simple-server with FFmpeg with as little latency as possible. The FFmpeg command is the code below.

The code does not through any errors by most of the frames are dropped, thus the effective frame-rate is 5 fps with about 10 sec of latency. I have not made any changes to the .yml file and so my question is there a FFmpeg command that already exist that can help this task? Also, should I modify the .yml file and if so, what changes are needed?

Thanks

Python OpenCV Code:
import cv2
import subprocess as sp

rtsp_server = 'rtsp://127.0.0.1:8554/mystream'
cap = cv2.VideoCapture('rtsp://192.168.0.6:8080/h264_ulaw.sdp')
sizeStr = str(int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))) + 'x' + str(int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT)))
fps = int(cap.get(cv2.CAP_PROP_FPS))

command = ['ffmpeg',
#'-re',
'-s', sizeStr,
'-r', str(fps), # rtsp fps (from input server)
'-i', '-',

        # You can change ffmpeg parameter after this item.
        '-pix_fmt', 'yuv420p',
        '-r', '30',  # output fps
        '-g', '1',
        '-c:v', 'libx264',
    '-tune', 'zerolatency',
        '-b:v', '3M',
        '-bufsize', '64M',
        '-maxrate', "4M",
        '-preset', 'fast',
        '-rtsp_transport', 'udp',
        '-segment_times', '5',
        '-f', 'rtsp',
        rtsp_server]

process = sp.Popen(command, stdin=sp.PIPE)

while(cap.isOpened()):
ret, frame = cap.read()
ret2, frame2 = cv2.imencode('.png', frame)
process.stdin.write(frame2.tobytes())

OUTPUT from RTSP Sever

[aler9]

The cause of the slowness is the fact that you're performing at least two re-encodings:

1. you're decoding every H264 frame and converting them into PNG, with the CPU
2. you're converting every png into H264, with the CPU

the server has no role in this; in my opinion, you can try this (but i won't give further details since it's not server related):

1. send raw RGB buffers to ffmpeg instead of sending PNGs; this eliminates the encoding into PNG
2. inside ffmpeg, encode to H264 with hardware acceleration; you need a Nvidia GPU and a specially-compiled ffmpeg:
   https://trac.ffmpeg.org/wiki/HWAccelIntro